Substituted 3, 6-dihydro-2h-1-thiapyrans and the process for producing them



United States Patent 3,073,845 SUBSTITUTED 3,6-DIHYDRO-2H-1-THIAPYRANSAND THE PROCESS FOR PRODUCING THEM William J. Middleton, tClaymont, DeL,assignor to E. I.

du Pont de Nemours and Company, Wilmington, Del.,

a corporation of Delaware No Drawing. Filed Dec. 18, 1959, Ser. No.860,348

21 Claims. (Cl. 260-327) This invention relates to, and has as itsprincipal objects provision of, novel heterocyclic organic compoundscontaining both sulfur and fluorine and a method for the preparation ofthe same.

A few dihydro-ZH-l-thiapyrans are known; however, none of these containsa fluorine-containing substituent. Because of the unusual propertiesimparted to organic compounds by fluorine substituents, it is adesirable goal to provide anew class of compounds having the dihydro-ZH-l-thiapyran ring structure and also having at least onefluorine-containing substituent.

A new class of dihydro-ZH-l-thiapyrans is provided by this invention.These novel compounds are 3,6-dihydro-ZH-Lthiapyrans having a fluorineor a fluorinecontaining substituent in the 2-position. Morespecifically, the products of this invention have the following generalformula:

in s X R5 C/ \C-/-Y wherein X is fluorine, R SR or the SR can be joinedwith an R of group Y, and wherein R is an a-fiuoroalkyl having up to 7carbon atoms; Y is X, chlorine, R, or SR, wherein R is an alkyl or anaryl having up to 7 carbon atoms; R and R are the same or different andcan be hydrogen, a monovalent hydrocarbon radical of up to 8 carbonatoms, or one of R and R taken with one of R and R can be a divalenthydrocarbon radical having 1-10 carbon atoms; R and R are the same ordifferent and can be hydrogen or a monovalent hydrocarbon radical of upto 8 carbon atoms; and R and R are the same or different and can behydrogen, fluorine, chlorine, monovalent hydrocarbon radical of up to 8carbon atoms, and R and R taken together can be a divalent hydrocarbonradical having up to 10 carbon atoms.

The compounds of this invention have been named in accordance withrecent Chemical Abstracts indexing practice in which the parent2H-l-thiapyran is:

In this name, the 21-1-1 indicates that the carbon in the 2-position ofthe ring is saturated and that the sulfur is in the 1-position. In the3,6-dihydro-2H-l-thiapyrans of this invention, the numerals 3 and 6refer to the positions of the other two saturated carbon atoms. Thecarbons in the 2, 3, and -positions may have one or both of theirhydrogen atoms replaced by other elements or radicals as defined above.

The fluorine-containing 3,6-hihydro-2H-1-thiapyraus of this inventionare prepared simply by contacting a conjugated diene of the formula3,3?3545 Patented Jan. 15, 1953 with a fluorine-containing thiocarbonylcompound of the formula i XCY wherein the symbols have the meaningsdefined hereinbefore. The reaction is a direct cyclo-addition reactionbetween 1 mole of the fluorothiocarbonyl compound and 1 mole of the1,3-diene. The sulfur of the thiocarbonyl group of thefluorothiocarbonyl compound becomes the ring sulfur of the thiapyranring and the carbon of the thiocarbonyl group becomes the saturatedcarbon in the 2-position of the thiapyran ring. The remaining carbons inthis ring are furnished by the 1,3-diene, i.e., the four chain carbonsof the conjugated 1,3-diene. This cycloaddition takes place by thewell-known Diels-Alder reaction. Thus, in this reaction the two-carbon-carbon double bonds in the land 3-positions of the diene breakand a valence bond from each of the land 4-carbons adds across and withthe double bond of the thiocarbonyl group to form the ZH-l-thiapyranring and the remaining two valence bonds from the broken carbon-carbondouble bonds in the 1,3-diene structure move inwardly toward each otherto form the carbon-carbon double bond between the 2- and 3-carbons ofthe diene residue. Consequently, the sulfur-containing 6-membered ringthat is formed contains one carbon-carbon double bond between the 4- andS-carbons of that ring. This reaction is illustrated by the followingequation in which the symbols X, Y, R R R R R and R have the meaningsdefined previously:

The process of this invention is a simple one and requires nocomplicated operating procedure or equipment. It is conveniently carriedout in a closed reaction vessel constructed of an inert material capableof withstanding the reactants and operating conditions, for example, ina glass or glass-lined reactor. Since many of the reactants are lowboiling and since many are quite reactive with the co-reactant beingemployed, the reaction is generally carried out by cooling the reactionvessel to a low temperature, e.g., the temperature of liquid nitrogen(about 196 C.) or of a mixture of solid carbon dioxide and acetone(about C.), then charging this reaction vessel with the 1,3-diene andadding the fluorine-containing thiocarbonyl compound, closing thereaction vessel and allowing the reaction to proceed until the color ofthe thiocarbonyl compound has disappeared. Generally, an exothermicreaction takes place and the reaction vessel can be cooled externally tocontrol the rate of reaction. The reaction vessel and its contents arethen warmed slowly to room temperature (20-30 C.). With higher boilingreactants, a closed reaction system is not necessary and in this casethe reaction can be conveniently carried out at atmospheric pressureunder reflux. In those cases where the heat of reaction is notsuflicient to carry the reaction to completion, the reaction mixture canbe heated externally, e.g., to a temperature of up to -l50 C. ifdesired.

Reaction times ranging from a few minutes, e.g., 5-. 10 minutes, up toseveral hours, e.g., 20-30 hours, depending on the reactivity of thespecific co-reactants and the particular operating temperature beingemployed. For example, hexafluorothioacetone reacts quantitatively with1,3-butadiene in less than 1 minute at -80 C., while 20 hours or moreare required for reaction of pentaflu- .ture by fractional distillation.

microns (C -C) 3 orothiopropionyl fluoride with anthracene at roomtemperature.

It is not necessary to employ a reaction medium in the process of thisinvention, but an-inert organic liquid can be used if desired. If areaction medium is used, it is preferred that it be anhydrous since manyof the thiocarbonyl compounds react rapidly with water. Any inert liquidorganic diluent can be used. Examples of suit .able diluents which canbe used as reaction media include hydrocarbons such as benzene, pentane,octane, cyclohexane, etc.; carbon bisulfide; polyfiuorinatedhydrocarbons such as perfiuorodimethylcyclohexane; and the like.

The 3,6-dihydro-2H-l-thiapyrans are isolated from the reaction mixtureby various means depending on the physical properties of the particularproducts. Normally liquid products are conveniently isolated from thereaction mix- Normally solid reaction products are conveniently isolatedby crystallization, followed by recrystallization from a solvent such aspentane. Discolored solid products can be purified by treatment withactivated carbon followed by recrystallization from a suitable solvent.

The products and processes of this invention are illustrated in furtherdetail by the following examples.

EXAMPLE I Butadiene, 10.8 g. (17.4 ml., 0.2 mole), is condensed into acalibrated receiver cooled to 78 C. Hexafiuorothioacetone is thendistilled into the receiver until a faint blue color persists. Thereaction mixture is allowed to warm to room temperature (25 C.) and isthen distilled. There is obtained 42.4 g., 90% of theory, of a colorlessoil boiling at 65 C./30 mm., refractive index, n of 1.4048.

Analysis.-Calcd for C H F S: C, 35.60%; H, 2.60%; F, 48.20%; S, 13.50%.Found: C, 36.32%; H, 2.67%; F, 46.92%; S, 13.87%.

The infrared absorption spectrum contains bands at 325 microns (=CH),3.4 and 3.5 microns (saturated CH and 5.95 microns (CH=CH). The nuclearmagnetic resonance fluorine spectrum contains a single sharp peak andthe proton spectrum contains three peaks in equal ratio.

These analytical data are in accord with a compound of the followingformula:

This compound is 2,2-bis-trifiuoromethyl-3,6-dihydro-2H- l-thiapyran.

EXAMPLE II 2,3-dimethylbutadiene, 8.2 g. (0.1 mole), is placed in areceiver and cooled to 78 C. Hexafiuorothioacetone, 12 g. (0.066 mole),is distilled into the receiver. The

blue color of the hexafluorothioacetone fades rapidly as The infraredabsorption spectrum contains bands at 3.35, 3.4 and 3.5 microns (CH andCH and 5.95

The fluorine nuclear magnetic resonance spectrum contains a single sharppeak, and the proton spectrum contains three peaks in the ratio of1:1:3. These analytical data indicate that the product has the formula:

S CF: HrC c oFs Hico H,

This compound is 2,2-bis-trifluoromethyl-3,6-dihydro-4,5-dirnethyl-2H-l-thiapyran.

EXAMPLE III Chloroprene (2-chloro-1,3-butadiene), 2.66 g. (0.03 mole),is placed in a receiver and cooled to 78 C. Hexafluorothioacetone isdistilled into the receiver until a faint blue color persists (5.46 g.being required). The reaction mixture is distilled and there is obtained6.1 g., 75% of theory, of a colorless oil boiling at 53 C./6 mm. andhaving a refractive index, 111323, of 1.4278.

Analysis.--Calcd for C H ClF S: C, 31.10%; H, 1.90%; Cl, 13.10%; S,11.80%. Found: C, 31.44%; H, 1.88%; Cl, 13.22%; S, 12.75%.

The nuclear magnetic resonance spectrum obtained indicates that theproduct is a mixture of the 4- and 5-chloroisomers in the ratio of about2:1. These analytical data indicate that the products have the followingformulas:

These compounds are 2,2-bis-trifluoromethy1-4-ch1oro-3,6-dihydro-2H-1-thiapyran and 2,2-bis-trifluoromethyl-S-chloro-3,6-dihydro-2H-l-thiapyran.

EXAMPLE IV These data indicate that the product has the followingformula:

Found:

110 s H CE:

This compound is 3,3bistrifluoromethyl-Zthiabicyclo- [2.2.1]hept-5-ene.This nomenclature for the product shows the fluorinated substituents (CPin the 3-position; however, it is readily seen from the above formulathat they are in the 2-position of the 2H-l-thiapyran ring which is partof the complete nucleus.

EXAMPLE V A reaction vessel is charged with 0.25 g. (0.014 mole) ofanthracene and 5 ml. of benzene and cooled to 10 C. To this suspensionis added 0.237 g. (0.013 mole) of hexafluorothioacetone and the reactionmixture is stirred vigorously until the blue color fades. The solutionis filtered and the filtrate is evacuated to dryness. The whitecrystalline residue that forms is recrystallized from pentane and thereis obtained 0.40 g., of theory, of long white needles melting at 123-124C. i

'5 Analysis.Calcd for C17H1OF6SI C, 56.67%; H, 2.80%; F, 31.64%; S,8.90%. FoundrC, 56.95%; H, 3.00%; F, 31.60%; S, 8,82%.

These analytical data indicate that the product has thefollowing'formula:

EXAMPLE VI A solution of 0.2 g. (0.0017 mole) of anthracene in 5 ml. ofcarbon disulfide is placed in a reaction vessel and there is then added0.4 g. (0.0017 mole) of perfluorobutanethione. The blue color of theperfiuorobutanethione fades rapidly and a sticky glass is obtained. Thisresidue becomes crystalline after standing for several days at ambienttemperature. The solid is recrystallized twice from pentane and there isobtained a White crystalline powder melting at 54-5 5 C.

AnaIysis.-Calcd for C H F S: C, 52.66%; H, 2.46%; F, 37.04%; S, 7.81%.Found: C, 53.16%; H, 3.08%; F, 36.85%; S, 7.69%.

The analytical data indicate that the compound has the followingformula:

i C no II II C EXAMPLE VII A mixture of 21.6 g. (0.82 mole) ofanthracene, 16 g. of trifluorothioacetyl fluoride (0.82 mole) and 50 ml.of benzene is sealed in a thick-walled glass tube and allowed to remainat room temperature overnight. The tube is cooled to C. and is thenopened. The liquid material is poured out and the solid remaining in thetube is dissolved in 50 ml. of warm carbon disulfide. The carbondisulfide solution is then combined with the liquid from the tube. Theresulting solution is treated with decolorizing carbon and then filteredand the filtrate is evaporated to dryness. The solid residue isrecrystallized twice from pentane solution (treated with decolorizingcarbon). There is obtained 27.2 g. of a cream-colored, granular solidmelting at C.

Analysis.-Calcd for C16H10F4SZ C, H, 3.25%; F, 24.49%; S, 10.33%. Found:C, 62.69%; H, p 3.62%; F, 23.91%; s, 10.03%. I5

6 These analytical data indicate that the compound has the followingformula:

This compound is 12-fiuoro-12-trifiuoromethyl-9,l0-dihydro-9,lO-epithiomethanoanthracene.

EXAMPLE VIII A reaction vessel containing 8.2 g. (0.01 mole) of 2,3-dimethyl-1,3-butadiene is cooled to 78 C. and trifluorothioacetylfluoride is distilled into the diene until a faint yellow color remains,13.2 g. being required. The reaction mixture is allowed to warm to roomtemperature and is then distilled. There is obtained 14.3 g., 67% oftheory, of a colorless liquid boiling at 45 C./2 mrn. having arefractive index, 11 of 1.4347.

Analysis.-Calcd for C H F S: C, 44.80%; H, 4.72%; F, 35.50%; S, 14.90%.Found: C, 45.11%; H, 5.10%; F, 35.21%; S, 14.12%.

These analytical data indicate that the compound has the followingformula:

l on.

This compound is Z-fluoro-2-trifiuoromethyl-3,6-dihydro-4,5-dimethyl-2H-l-thiapyran.

EXAMPLE IX A reaction vessel is charged with 6.6 g. (0.1 mole) offreshly distilled cyclopentadiene and is cooled to --78 C.Trifluorothioacetyl fluoride is distilled into the reaction vessel untila faint yellow color persists in the reaction mixture, 13.2 g. beingrequired. The reaction mixture is allowed to warm to room temperatureand is then distilled. There is obtained 2.7 g., 14% of theory, of acolorless liquid boiling at 45 C./ 7 mm. and having a refractive index,n of 1.4396, and 16 g. of a clear glassy polymeric residue.

Analysis.Calcd. for CF H F S: C, 42.42%; H, 3.05%; F, 38.36%; S, 16.17%.Found: C, 42.30%; H, 3.25%; F, 38.08%; S, 16.41%.

The fluorine nuclear magnetic resonance analysis of the liquid indicatesit to be a mixture of isomers in the ratio of about 2:7. Theseanalytical data indicate that the monomeric products have the formulas:

These monomeric compounds are the geometric isomers of 3-fiuoro 3trifiuoromethyl-Z-thiabicyclo[2.2.1]hept- 5-ene. The solid product is apolymer of these monomeric isomers.

EXAMPLE X tive index, n of 1.4213. The nuclear magnetic resonancespectrum of this product indicates that it has the following formula:

E This compound is 2-fiuoro-2-trifluoromethyl-3,6-dihydro-ZH-I-thiapyran.

A sample of the product of Example X stored at room temperature for oneweek etches its glass container badly. The material from this containeris redistilled and elemental and nuclear magnetic resonance analysis ofthe redistilled product indicate that it has lost hydrogen fluoride.

Analysis.-Calcd. for C H F S: C, 43.40%; H, 3.00%; F, 34.30%; S, 19.30%.Found: C, 43.60%; H, 3.55%; F, 34.10%; S, 19.55%.

The infrared absorption spectrum showing bands at 6.1 microns and 6.35microns is consistent with the assignment of the structure of thiscompound as 6-trifluoromethyI-ZH-I-thiapyran.

EXAMPLE XI Thiocarbonyl fluoride, 10 ml. (14 g., 0.017 mole) is slowlydistilled into a reaction vessel containing 14 ml. (11.2 g., 0.17 mole)of freshly distilled Cyclopentadiene cooled to -78 C. During theaddition of the thiocarbonyl fluoride, the reaction mixture is stirredand kept below C. with a cooling bath. When the addition is complete, 30minutes being required, the reaction mixture is allowed to warm to roomtemperature and is then evacuated to 1 mm. mercury pressure by means ofan oil pump. During the evacuation the reaction mixture solidifies to awhite granular solid. There is obtained g. of the white solid, M.P.47.5-48.5 C. A. small sample is sublimed for analysis.

AnaIysis.--Calcd for C H F S: C, 48.64%; H, 4.10%; F, 25.60%; S, 21.60%.Found: C, 48.37%; H, 4.19%; F, 25.07%; S, 21.36%.

The fluorine nuclear magnetic resonance spectrum shows the WSSW patternwith one side split into doublets. The infrared absorption spectrumhaving bands at 3.25, 3.35, 3.4 and 6.55; microns is consistent with thestructure proposed below. These data indicate that the compound has theformula:

E This compound is 3,3-difluoro-2-thiabicyclo[2.2.1]hept- S-ene.

When the product of Example XI is stored at room temperature for severaldays, or heated above its melting point for a few minutes, itpolymerizes to a white rubbery polymer.

A stable derivative is made by adding bromine to the product of ExampleXI. Bromine is added dropwise to a solution of 1.48 g. (0.01 mole) ofthis product in 2 ml. of carbon tetrachloride until a slight brominecolor remains. The reaction mixture is cooled in a bath of acetone andsolid carbon dioxide and the solid that precipitates is collected on afilter and recyrstallized from pentane. There is obtained 1.89 g. of4,6-dibromo-3,3- difluoro-Z-thiabicyclo[2.2.1]heptane.

Analysis.-Calcd for C H Br F S: C, 23.40%; H, 2.00%; Br, 51.90%; F.12.30%; S, 10.40%. Found: C, 23.91%; H, 2.19%; Br, 52.26%; F, 11.60%; S,10.20%.

EXAMPLE XII 2,3-dimethyl-1,3-butadiene, l g. (0.012 mole), is add- H Hoed dropwise to 2.26 g. (0.01 mole) of perfiuorodithiobutyrolactonecooled to 0 C. by means of an ice bath. When the initial exothermicreaction has subsided and the red color has faded to yellow (about 5minutes being required for this reaction), the reaction mixture isdistilled. There is obtained 2.16 g., 70% of theory, of a light yellowoil boiling at 67-68" C./ 0.75 mm. and having a refractive index, 11, of1.4677.

Analysis.-Calcd for C H F S C, 39.00%; H, 3.00%; F, 37.00%; S, 20.70%.Found: C, 39.40%; H, 3.93%; F, 36.89%; S, 21.02%.

These analytical data indicate that the product has the followingformula:

This compound is2,3,4-hexafiuoro-8,9-dimethyl-1,6-dithiaspiro[4.5]dec-8-ene.

EXAMPLE XIII A reaction vessel is charged with 1.36 g. (0.00513 mole) ofbis-trifluoromethyl-trithiocarbonate and cyclopentadiene is addeddropwise until the red color of the trithiocarbonate is discharged.Approximately 1 minute is re quired for the addition of 0.34 g. ofcyclopentadiene. The reaction product is distilled and there is obtained1.1 g., 70% of theory, of a light yellow oil boiling at 63 C./ 1.3 mm.and having a refractive index, of 1.4893.

Analysis.-Calcd for C H F S S, 30.80%. S, 30.32%.

These analytical data indicate that the product has the followingformula:

Found:

This compound is3,3-bis-trifiuoromethylthio-2-thiabicyclo[2.2.1]hept-5-ene.

EXAMPLES XIV, XV, AND XVI HO C\ 0 H3-chloro-3-trtfluoromethyl-2-thiablcyclo[2.2.1]hept-5-ene Example No. XV

H C S Hi l H2 0 GCIF \l/ C H Example N0. XVI

3-ch1oro-3-trifluoromcthylthio-2-thlabicyclo[2.2.1]hept-5-ene EXAMPLEXVII These analytical data indicate that the product has the followingformula:

H H H o o 0 t i i D HC\ /0 n H/| H This compound is12-fluoro-12-pentafiuoroethyl-9,10-dithydro-9,-epithiomethanoanthracene.

. EXAMPLE XVIII A mixture of 4.5 g. (0.055 mole) of 2,3-dimethyl-1,3-butadiene and 5.22 g. (0.03 mole) of ethyl trifiuorodithioacetate isstirred at 0 C. for 7 hours and is then allowed to warm to roomtemperature and stand overnight. The reaction mixture is distilled andthere is obtained 6.9 g. of a colorless oil boiling at 72 C/0.8 mm. andhaving a refractive index, u of 1.4940.

Analysis.-Calcd for 'C H F S C, 46.85%; H, 5.90%; F, 22.24%; S, 25.01%.Found: C, 47.16%; H, 6.24%; F, 22.28%; S, 25.23%. These analytical dataindicate that the product has the following formula:

/so211. C-OF:

whereupon the color disappears rapidly and a waterwhite solutionresults. The product is stable at 80 C. but quickly darkens at roomtemperature. Fluorine nuclear magnetic resonance analysis indicates thatthe prod not is a mixture of the two geometric isomers (in the ratio of15:85) of the following formulas:

H C /.L\S H2 1 t no and H no S ll HG SCFa These compounds are3-fluoro-3-trifluoromethylthio-2- thiabicyclo[2.2.1]hept-5-enes.

EXAMPLE XX A purple mixture of trifluorothioacetone and trifiuoroacetone(obtained on distillation of reaction mixtures containing 1,1,1trifluoro 2 hydroxy 2 mercaptopropane at atmospheric pressure) is mixedwith 2,3-dimethyl-1,3-butadiene at slightly above C. whereupon thepurple color is rapidly discharged. Distillation of the colorlessreaction mixture affords a colorless oil boiling at 99 C./ 34 mm. andhaving a refractive index, n of 1.4533.

Analysis.Calcd for C H F S: C, 51.49%; H, 6.23%; F, 27.10%; S, 15.25%.Found: C, 51.14%; H, 6.53%; F, 27.00%; S, 15.75%.

These analytical data and the nuclear magnetic resonance spectrumobtained on'the product indicate that the product has the followingformula:

(3H3 This compound is 2-trifluoromethyl-3,6-dihydro-2,4,5-trimethyl-ZH-l-thiapyran.

EXAMPLE XXI A reaction vessel containing the 1,1,2,2-tetrafluoro-3-pentanethione obtained by pyrolysis of 3.8 g. of 1,1,2,2tetrafiuoro-3,3-dimercaptopentane at 550 C. under a pressure of 1 mm. Hgor less and 3.0 ml. of 2,3-dimethyl-1,3- butadiene at 196 C. undervacuum is warmed to 80 C. and the reactants are mixed by shaking thevessel. On warming the reaction mixture slightly above 80 C., themagenta color of the fluorothioketone is discharged as rapid reactionoccurs. Distillation of the reaction mixture affords the 1:1 adduct as acolorless oil, B.P. 107.5108.5 C./8 mrn.; 11 1.4612.

Analysis. Calcd. for C H F S: F, 29.61%; S, 12.51%. Found: F, 29.79%; S,13.21%. This compound is 2-ethyl-2-(1,1,2,2-tetrafluoroethyl)-3,6-dihydro-4,5-dimethyl-2H-l-dithiapyran having the following formula:

EXAMPLE XXII A reaction vessel containing the trifiuorothio-acetophenoneobtained by pyrolysis of 3.3 g. of 1,1-dimercapto-2,2,Z-trifluorophenylethane at 550 C. under a pressure of less than 1mm. Hg and 6 ml. of 2,3-dimethyl-1,3-butadiene at -80 C. is warmedslightly whereupon the reactants melt. On shaking the liquid reactionmixture, the materials react with discharge of the blue colorof thefluorothioketone. Distillation of the reaction mixture gives a colorlessoil, B.P. 96 C./0.5 mm.; 11 2 1.5242.

Analysis. Calcd. for C H F S: F, 20.90%; 8, 11.78%. Found: F,21.06%; S,12.05%.

1 1 This compound is2-trifluoromethyl-3,6-dihydro-4,5-dimethyI-Z-phenyl-ZH-l-thiapyranhaving the formula:

/S\ /CF:

dioxide. There is obtained 18.2 g. of a white solid, M.P. 20-21" 0., 111.4162.

Analysis. Calcd. for C H F OS: C, 33.60%; H, 1.60%; F, 45.60%; S,12.80%. Found: C, 33.78%; H, 1.79%; F, 45.84%; S, 12.71.

These analytical data indicate that the product has the followingformula:

Analysis.-Calcd. for (C H F OS) C, 33.60%; H, 1.60%; F, 45.60%; S,12.80%. Found: C, 33.10%; H, 1.65%; F, 44.50%; S, 13.05%.

This polymer becomes sticky when warmed to 40 C. and is useful as anadhesive for joining sheets of paper together.

EXAMPLE XXIV Two moles of hexafluorothioacetone reacts with one mole ofstyrene as indicated by the following equation:

H (orisomer) Styrene is added dropwise to 1.9 g. (0.05 mole) ofhexafluorothioacetone in a reaction vessel cooled to -78 C. until theblue color of the thioketone fades completely. The reaction product isthen distilled and there is obtained 7.1 g. of a colorless, viscous oil,B.P. 103-104" C./1.2 mm. and having a refractive index, n of 1.4518. Thenuclear magnetic resonance hydrogen and fluorine spectra obtained onthis product indicates that a mixture of isomers of the formula givenabove is present. Thus,

these products are3,7,8,8a-tetrahydro-Z,2,7,7-tetrakis(trifluoromethyl)-5,8-etheno-2H, 5Hthiapyrano[4,3-b] thiapyran, and its isomers.

12 EXAMPLE POCV As in Example XXIV, 1,1'diphenylethylene reacts with 2moles of hexafluorothioacetone in accordance with the followingequation:

A solution of 1.8 g. of 1,1-diphenylethylene in 10 m1. of pentane isadded dropwise to 1.82 g. (0.01 mole) of hexafluorothioacetone in areaction vessel cooled to -78 C. The blue color fades and a white solidprecipitates during a period of 2-3 minutes. The solid is collected on afilter, washed with cold pentane and recrystallized from cyclohexane.There is obtained 2.5 g. of colorless crystals, M.P. l52-153 C.

Analysis.-Ca1cd for CggHmFsSI C, H, 2.23%; F, 41.88%; S, 11.78%. Found:C, 44.40%; H, 2.68%; F, 41.65%; S, 11.84%.

The nuclear magnetic resonance and infrared absorption spectra obtainedon this product indicate that the compound has the structure shownabove. This compound is 3,7,8,8a-tetrahydro 2,2,7,7tetrakis(trifiuoromethyl)-5,8-etheno-4-phenyl 2H,5H thiapyrano[4,3-

b] thiapyran.

EXAMPLE XXVI Approximately equimolar amounts of anthracene and theorange-red fluorothioformyl cyanide (prepared by reaction offluorochloroacetonitrile with sulfur at 600- 650 C.) are mixed in areaction vessel at 80 C. The reaction mixture is then allowed to warmgradually to room temperature during which time the decolorization ofthe fluorothioformyl cyanide is complete. Evaporation of the solution todryness followed by two recrystallizations of the residue from benzenegives colorless crystals of pure12-cyano-12-fiuoro-9,10-dihydro-9,10-epithiomethanoanthracene, M.P.139-142 C.

Analysis.-Calcd for C H FNS: C, 71.90%; H, 3.77%; F, 7.11%; N, 5.24%; 8,11.99%. Found: C, 71.45%; H, 3.75%; F, 6.77%; N, 5.57%; S, 12.30%.

These analytical data and the infrared absorption spectrum obtained onthe product are in agreement with the compound of the following formula:

cene is pyrolyzed back to the starting materials by heating underreduced pressures, e.g., by heating (by means CH S/F CH O\ of a freeflame) the adduct in a reaction vessel under other 3,6 dihydro-2H-l-thapyrans of the general formula a pressure of 05-100 mmfHg. definedpreviously. Other specific products of this in- In addition to thespecific compounds illustrated in vention and the reactants from whichthey are made the examples, the products of this invention include arelisted inthe followingtable:

Table l Reactants Product 1,3-diene a-Fluorothiocarbonyl compound H H CI H2? CH CFaCFzfiF HG CH2 S F H2O (2H s H L H H:

0 H O CFr-CF! H C l HzC OH HClFCfiF HO (EH S ml 1 4| r f l H2O OH HO CH20 C CHCIF H C H CH3 S F H CH =C- =GH CFFCFCFZfiF H2O C-CFOF=CF HsC-C CH2(and 4-CH3 isomer) CqH5 C5115 112C]? C-OF2H CH7=OC=CH1 2 H CsH5C CH2 t05155 CH3CH=OH-CH=CH2 CHaCFfiF EMU-(l1 C-CFzCHs HG CH2 c H t (or 3-OHaisomer) H S 01 CH3(CHz)3OH=OH-CH=CH2 C1CF2(CF2)3%C1 CHa(CH2)s lC|-(CF2)3CF:C1

S HC\ /OH2 (or 3-C4H9 isomer) H S CF21 .t\/\/ CHaCHzCH=CH-CH=CHCH2CH& Cfll l i a- Fs S H0 CH C CzHg H II Cl Cl OFz---C V CH S SQF I..GH:=C-+O=OH1 S 01-0 O CF,

7 V CFrCF C F1 '.C-CH1 GIG-CF;

H F TS G1} V CH =CH CFafiCzFi @1 20 0-4323;

The conjugated dienes used in the process of this invention are commonlyavailable or can be made by known methods.

The fluorine-containing thiocarbonyl compounds used in the reaction withthe conjugated dienes can be prepared by various methods applicable tothe 65 various types of fluorothiocarbonyl compounds as described below.

The a-fluorothioacyl fluorides can be prepared by dehydrofluorination,by means of sodium fluoride, of the mercaptans formed from the additionof hydrogen sul- 70 than one fluorine atom).

This dehydrofluorination is conveniently carried out at ordinarytemperature and reduced pressure.

The a-fluorothioacyl fluorides can also be prepared by sodium fluoridedehydrofluorination of 75 The ot-fluorothioacyl chlorides used in theprocess of this invention can be prepared by various methods, some ofwhich are described below. A general method for preparing thefluorothioacyl chlorides comprises contacting a fluorochloro-alkane ofthe formula XR CY CI, wherein X is fluorine, chlorine, or hydrogen, Y ischlorine, bromine, or iodine, and R is perfluoroalkylene, preferablyperfluoroalkylene having 1l0 carbon atoms, with sulfur at temperaturesat which the sulfur is in vapor form. At atmospheric pressure, thereaction temperature is about 445 C. At higher or lower reactionpressures, the reaction temperatures are raised orlowered accordingly.

Some fluorothioacyl chlorides can be prepared by contacting achlorofluor-oalkyl mercury compound of the formula (CF CClZ) Hg, whereinZ is bromine or chlorine, with hot liquid or vapor of sulfur. In thisreaction, the chlorofluoroalkyl mercury compound is preferablyintroduced gradually into an excess of refluxing sulfur (at atemperature of 445 C.) under a blanket of an inert gas, e.g., nitrogen,and the volatile fluorothioacyl chloride that is formed is collected ina receiver cooled to a temperature below the boiling point of thefluorothioacyl chloride (Middleton, Serial No. 833,913, filed August 17,1959).

The fluoroalkyl mercury compounds used in the proc ess described in thepreceding paragraph .can be prepared by reaction of fluoroolefins of theformula of ZCCl==CF wherein Z is bromine or chlorine, with mercuricfluoride at elevated temperatures, e.g., 100 C., by the processdescribed in greater detail in U.S. Patent 2,844,614 to C. G. Krespan.

Still another method for preparing fluorothioacyl chloridescomprises thethermal decomposition of chlorinated fluoroalkyl-1,3-dithietanes asillustrated by the following equation:

ZXRtCCl wherein X is fluorine, chlorine or hydrogen and R isperfluoroalkylene. This decomposition is generally effected attemperatures between 450 and 700 C. and preferably at reduced pressure(Middleton, Serial No. 833,913).

The acyclic esters of fiuorodithiocarboxylic acids used as startingmaterials in the process of this invention can be prepared by reactionof a thiol of the formula RSH, where R is alkyl or haloalkyl, and analkali metal fluoride with a compound of the formula R CF SH or R CSF,where Rf is a haloalkyl radical having fluorine on the acarbon. In thisreaction, an amount of alkali metal fluo ride is used that is equivalentto the amount of hydrogen fluoride being removed from the reactants,i.e., 2 moles of alkali metal fluoride per mole of fluorinated thiol or1 mole of alkali metal fluoride per mole of fluorothioacyl fluoride.Preferably up to a -fold excess of alkali metal fluoride is issued. Onemole of the thiol RSH is required for each mole of the fluorinated thiolor fluorinated thioacyl flouride employed. However, an excess of thethiol RSH is generally used, the excess thiol serving as a solvent orreaction medium. The reaction takes place to some extent'at least attemperatures of 25 C. or even lower. However, the reaction proceedsfaster at temperatures above 0 C. and a temperature of between and 75 C.is preferred (Middleton, Serial No. 836,603, filed August 28, 1959).

The cyclic esters of fluorodithiocarboxylic acids used in the process ofthis invention can also be prepared by various methods. One methodinvolves the pyrolysis of fluorodispirotrithiahydrocarbons, e.g.,perfluorodispiro [3.1.3.2]-5,l0,ll-trithiaundecane, at temperatures of450- 800 C. at reduced pressures. The pyrolysis products are collectedin receivers cooled to low temperatures, e.g., the temperature of amixture of solid carbon dioxide and fiuoroketones used as startingmaterials in this method.

.18 acetone, and the cyclic esters .of fluorodithiocarboxylic. acidsthatare formed are isolated by fractional distillation.

The fluorodispirotrithiahydrocarbon starting materials for the processdescribed in .the preceding paragraph can be prepared by treatment of afluorocycloalkanone with phosphorus pentasulfide at temperatures ofabout 210 C. for several hours followedby fractional distillation toisolate the desired dispirotrithiahydrocarbon.

Another method for the preparation of the cyclic esters offluorodithiocarboxylic acids used in the process of this inventioninvolves the reaction of an oz,w-diiodofluoroalkane with hot liquid orvapor of a phosphorus polysulfide, e.g., P 8 .or P S .In this process,the diiodofluoroalkane is preferably introduced in vapor form into therefluxing phosphorus polysulfide and the volatile.fluorodithiocarboxylic acid ester which is formed is collected inareceiver'cooled below the boiling point of the product (Middleton,Serial 836,601).

The u-fluorothioketones used in the process of this invention can beprepared by various methods. One method involves reacting a secondarypolyfluoroalkyl iodide (i.e., of at least 3 carbon atoms) with hotliquid or vapor of a phosphorus polysulfide. In this process, thepolyfiuoroalkyl iodide is preferably introduced in vapor form intorefluxing phosphoruspolysulfide and the volatile polyfluorothioketonewhich is formed is collected in a receiver cooled below the boilingpoint of the polyfluorothioketone, e.g., in a trap cooled by a mixtureof solid carbon dioxide and acetone. The secondary polyfluoroalkyliodides used in this processcan be made by knownmethods. For example,they can be made by the free radical addition of the appropriatefiuoroalkyl iodide to a fluoroolefin. This and other methods forpreparing fluoroalkyl iodides are described'in Aliphatic FluorineCompounds by Lovelace, Rausch and Postelnek, Reinhold PublishingCorporation, New York (1958), pp. 37-40. (Howard & Middleton, U.S.application Ser. No. 791,857, filed February 9,1959.)

Another method for preparing polyfluorothioketones consists in heating apolyfluoroketone with phosphorus pentasulfide for several hours atelevated temperatures, e.g., ZOO-300 C. under autogenous pressure. Thepolycan be prepared by known methods, e.g., those described on p. 183 ofAliphatic Fluorine Compounds, referred to above (Howard & Middleton,lac. cit.).

Partially fluorinated thioketones of the type illustrated by1,1,l-trifluorothioacetone can be made by thermal decomposition attemperatures ranging from to 750 C. of the corresponding gem.-dithiolsor ol-thiols which are in turn obtained by treatment of thecorresponding fluorinated ketones with hydrogen sulfide in the presenceor absence of phosphorus pentoxide (Kealy CR 5367, filed herewith).

The 3,6-dihydro-2H-l-thiapyrans of this invention are useful in avariety of applications. They are particularly useful as a means forstoring u-fluorothiocarbonyl compounds which are relatively unstablesince they can be pyrolyzed back to the starting materials when they areneeded. The adducts of anthracene and fluorothiocarbonyl compounds areparticularly useful in this respect.

The products of this invention are also useful as fumigants. Thus, the3,6-dihydro-2H-l-thiapyrans can be heated to decompose the adduct intotheir starting dienes and a-fiuorothiocarbonyl com-pounds. Thea-florothiocarbonyl compounds, particularly the fluorothioacyl fluoridesand chlorides, are especially effective fumigants and insecticidesagainst ordinary houseflies. Consequently, the products of thisinvention are particularly useful for generating the effectiveinsecticide and furnigant in the location to be treated.

The products of this invention are also useful as plasticizers andsofteners for polymeric materials such as polythiocarbonyl fluoride.

The 3,6-dihydro-2H-l-thiapyrans can also be polymerized by additionpolymerization to polymers that are useful as adhesives, coatingcompositions, plastics and elastomers.

Since obvious modifications and equivalents in the invention will beevident to those skilled in the chemical arts, I propose to be boundsolely by the appended claims.

The embodiments of the invention is which an exclusive property orprivilege is claimed are defined as follows:

1. 2,2-bis-trifiuoromethyl-3,6-dihydro-2H-l-thiapyran.

2. 2,2-bis-trifluoromethyl 3,6-dihydro 4,5-dimethyl- 2H-1-thiapyran.

3. A 2,Z-bis-trifiuoromethyl-chloro-3,G-dihydro-ZH-L thiapyran.

4. 3,3-bis-trifiuoromethyl-Z-thiabicyclo[2.2.1]hept 5- ene.

5. 12,12-bis-trifiuoromethyl-9,10-dihydro-9,10 epithiomethanoanthracene.

6. 2,3,4-hexafluoro-8,9-dimethyl 1,6 dithiaspir[4.5] dec-S-ene.

' 7. 2,2-bis-trifluoromethyl-3,6-epoxy-3,6 dihydro 2H- l-thiapyran.

8. 3,7,8,8a-tetrahydro 2,2,7,7tetrakis(trifluoromethyl)-5,8-etheno-2H,5H-thiapyrano[4,3-b1thiapyran.

9. 12-cyano-12-fluoro-9,IO-dihydro 9,10-epithiomethanoanthracene.

10. A 2,2-bis-fiuoroalkyl-3,6-dihydro-2H l-thiapyran in which the alkylgroup contains up to 7 carbon atoms.

11. 3,3-difiuoro-2-thiabicyclo[2.2.1]hept-5-ene.

12. 3-chlorodifiuoromethyl-3-ethylthio 2 thiabicyclo [2.2.1]hept-5-ene.

13. 3,7,8,8a-tetrahydro-2,2,7,7-tetrakis(trifluoromethyl)-5,8-etheno-4-phenyl 2H,5H thiapyrano[4,3-b]thiayran.

p 14. 2-fiuoro-2-trifluoromethyl3,6-dihydro-4,5-dimethyI-ZH-I-thiapyran.

15. 2-fluoro-2-trifiuoromethyl 3,6-dihydro-2H-1-thiapyran.

16. 2-trifluoromethyl-Z-ethylthio 3,6dihydro-4,5-dimethyl-ZH-l-thiapyran.

17. 2-trifluorornethyl-3,6-dihydro-2,4,5 trimethyl-ZH- l-thiapyran.

l8. 2-ethyl-2-(l,l,2,2-tetrafluoroethyl) 3,6 dihydro-4,S-dimethyl-ZH-l-dithiapyran.

20 I9. 2-trifiuoromethyl-3,6-dihydro 4,5 dimethyl-2-phenyl-ZH-l-thiapyran. 20. A process for preparing the compounds ofclaim 21 which comprises contacting, at reaction temperature, a compoundof the formula:

F ?E R5 R4 R3 R: with a compound of the formula:

8 ll XCY wherein X, Y and the Rs are defined as in claim 21.

21. A compound of the formula wherein X is selected from the groupconsisting of 1) monovalent fluorine and a-fluoroalkyl anda-fiuoroalkylthio of up to 7 carbons and (2) divalenta-fluoroalkylenethio of up to 7 carbons the free valence of which isjoined to divalent Y; Y is selected from the group consisting of (l)monovalent fluorine, chlorine, and aryl hydrocarbon, alkyl alkylthio,a-fluoroalkyl and a-fluoroalkylthio of up to 7 carbons and (2) divalenta-fiUOI'O- alkylenethlo and a-fiuoroalkylene of up to 7 carbons the freevalence of which is joined to divalent X; R and R are selected from thegroup consisting of hydrogen and monovalent hydrocarbon of up to 8carbons free of nonaromatic unsaturation; R and R are selected from thegroup consisting (1) separately, of monovalent hydrogen and hydrocarbonof up to 8 carbons free of nonaromatic unsaturation and (2), jointly, ofdivalent hydrocarbon of up to 10 carbons free of nonaromaticunsaturation; and R and R are selected from the group consisting (l),separately, of monovalent hydrogen, fluorine, chlorine and hydrocarbonof up to 8 carbons free of nonaromatic unsaturation and (2), jointly, ofdivalent hydrocarbon of up to 10 carbons free of nonaromaticunsaturation.

No references cited.

1. 2,2-BIS-TRIFLUOROMETHYL-3,6-DIHYDRO-2H-1-THIAPYRAN.
 20. A PROCESS FORPREPARING THE COMPOUNDS OF CLAIM 21 WHICH COMPRISES CONTACTING, ATREACTION TEMPERATURE, A COMPOUND OF THE FORMULA:
 21. A COMPOUND OF THEFORMULA